Agricultural Research Service scientists from Albany, Calif., compared 11 different amino acids in three types of oranges from healthy trees, symptom-free but infected trees and infected trees, according to a news release.
University of California, Davis, professor Carolyn Slupsky, also participated in the research.
They used nuclear magnetic resonance spectroscopy to study the amino acid composition, and it also marked the first time this technology was used for that purpose.
Using amino acids as an HLB-detection method will require further research, but the chemicals also may reveal clues to mechanisms underlying the greening bacterium's mode of attack.
For example, the tree uses amino acid phenylalanine to make other compounds thought to be important in the tree's defense system.
Researchers found that orange juice from HLB-infected trees had significantly higher concentrations of phenylalanine, suggesting that pathogen may interfere with the tree's conversion of the amino acid to defense compounds.